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OREGON STP
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APR 23
Orange Tortrix
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R. G'. Rosenstiel
Agricultural Experiment Station
Oregon State College
Corvallis
Circular of Information 524
February 1953
aué
ee Orange Tortrix
R. G. ROSENSTIEL
Associate Entomologist
The orange tortrix has been a greenhouse insect pest for several years in
Oregon and has been a pest of oranges in California for many years. Early in 1947
it began to appear in numbers on various cane fruits in Nultnomah County. During
1948 field control of the larvae of this moth was worked out and growers who treated
Samples of fruit from
their plants as directed escaped injury to their fruit.
treated fields were analyzed for chemical residue so that a safe and reliable control
program could be devised.
The Insect
The larvae ol' the orange tortrix are yellowish green "worms" with browii heads.
The larvae are one-sixteenth of an inch long at the time of hatching and are an inch
long when full grown. The larvae feed in the new, tender terminal leaf growth on
their host plants where they web the leaves slightly together. When the berries
ripen, some of the worms leave the terminal shoots and enter the base of' the berries
They have been found in fruit of blackberries,
to feed on the inside of the fruits.
Boysens, Logans, and Youngberries, but have not been observed in raspberry fruits in
fields. As the pickers deposit raspberries in their picking baskets, the larvae are
The pickers contact the
disturbed and drop from the leaves on a strand of silk.
silken strands and carry them with the attached larvae to the boxes of fruit. Thus
the tortrix larvae get on the fruit and are carried to the canneries where their
presence is objectionable.
The orange tortrix declined in numbers after 1948 so that it was scarce in
1950 to 1952. It may return, so berry growers and others should watch for it in
the spring of the year.
This insect overwinters in Oregon as both large and small larvae beneath such
shelters as dead leaves caught on the thorns of the canes, in galls on the canes,
and in other places protected from rain.
The orange tortrix' eggs are laid in flat masses on the smooth canes and on
the bottom side of some of the leaves. The pupae are found among webbed leaves on
the host plant and in debris. There are several generations of the tortrix each
year. Due to the uneven age of the overwintering larvae, the following generations
are mixed so that eggs, adults, larvae, and pupae may generally be found in infested
crops at any one time during the suniiner.
Note: In addition to the orange tortrix, the larvae of' the oblique-banded
leaf roller may be on some of the cane fruits. The large larvae of the obliquebanded leaf roller may be distinguished by their black heads from the brown-headed
tortrix larvae. See Ecperiinent Station Circular of Information 352 for obliquebanded leaf roller control by use of DDT.
This publication is revised from and is to supersede Circular of
Note:
Information 426, now out of print.
Hosts
The orange tortrix has been found feeding outdoors in Oregon on raspberry,
Loganberry, Youngberry, Boysenberry, and Himalaya blackberries. It may have other
outdoor hosts, as it feeds on many greenhouse plants.
Di st rib ut ion
The tortrix in 1947 was known to be in a half mile square area located 2 miles
southwest of Gresham. By the fall of 1948 it had spread in Nultnomah County north
to the Columbia River, westward to Portland, and eastward to a line from Troutdale
to Pleasant Home. In Clackamas County, tortrix larvae spread as far east as Dodge
No tortrix larvae were found
Park and as far west as 2 miles west of Clackamas.
south of a line through Clackamas and Damascus. Growers within or near the area of
infestation would be wise to examine their cane berries closely after a few leaves
have unfolded in the spring.
Field Examination
If tortrix larvae are present in the spring or summer they will be in the bud
tips or webbing the edges of the leaves. In 1948 the presence of any tortrix
larvae in a field in the spring was sufficient cause for recommending treatment.
Such procedure would be justified as a means of preventing the increase in tortrix
population, particularly in areas where growers had found numerous tortrix the
preceding season. Tortrix larvae are not easy for growers to find in the fields
unless careful examinations are made at not longer than monthly intervals in the
spring in all parts of the field.
Control Measures
During the fall of 1947 and the season of 1948 the following timing of applications of the chemical TDE (Rhothane) was very effective in controlling the orange
tortrix on cane berries. The insecticide may be applied either as a dust or as a
spray.
It should be used at the rate of either 40 pounds per acre of a 5 per cent
TDE dust or at the rate of 150 to 180 gallons per acre of a spray mixture containing
1 pound of the 50 per cent wettable powder to 100 gallons of water. If the spray is
used it should be directed upward so that the underneath sides of the leaves are
thoroughly wetted.
Spring application
When the first leaves are fully open the tortrix larvae break their winter
rest and feed on the new foliage and buds. This period in 1948 was May 5 to 15.
Before that time some larvae were not yet feeding and after that time some larvae
were entering the inactive pupa stage.
In the spring the grower has fewer leaves
to contact than he would have later in the summer, so spring is the ideal time to
control the tortrix. TDE is not compatible chemically with lime sulfur.
Consequently, the spring application of TDE should be applied at least 10 days after the
lime sulfur spray.
3
Summer application
If a suimner dust or spray treatment is necessary, it should be applied in the
period 10 to 20 days before harvest time to avoid having excess chemical residue on
the harvested fruit. This period will vary for the different kinds, since raspberries ripen first in the spring followed by Logans, then Boysens, and finally
Himalaya blackberries. Not more than one pound of the 50 per cent TDE to 100 galions should be used in the sununer treatment.
TDE in amounts greater than recommended, when applied to infested plants in
the sumnier, may reduce the number of natural tortrix parasites and cause a chemical
residue problem. TDE is very effective for orange tortrix control and has considerable residual value. It should not be applied at stronger rates than suggested
above and it should not be necessary to apply it more than twice a season and then
only in severely infested fields.
Control Summary
Time
Chemical and dosage
Spring ........ 5% TDE dust at the rate of 40 pounds
per acre or 1 pound of 50% TDE wettable powder per 100 gallons of water.
At least 150 gallons per acre of spray
should be applied,
Summer
4.0 pounds per acre or
5% TDE dust
1 pound of 50% TDE wettable powder
per 100 gallons of water. At least
l0 gallons per acre of spray should
be alied.
Notes
Apply in early May
when first leaves unfold. Use 2 pounds of
TDE 50% wettable powder
to 100 gallons of water
in severe infestations.
Apply 10 to 20 days before fruit picking time.
Do not use greater
amounts than those
recommended.